Carbon Fiber & Composites Feeds & Speeds Chart
Quick-look reference data for CFRP, GFRP, and aramid composite routing, trimming, and light milling. Use it as a chart-first starting point before you validate cutter diameter, laminate stackup, and dust control in the plastics calculator.
Need Exact Composite Routing Numbers?
Use this chart for a fast first pass. Then move to the plastics calculator when cutter diameter, coating choice, laminate behavior, or edge-quality risk need a setup-specific answer.
What This Chart Covers Best
First-pass SFM and chip-load windows for routing, edge trimming, and light milling across CFRP, GFRP, and Kevlar-style laminates.
Where It Needs Backup
Holemaking needs feed-per-rev, breakthrough, and backer support logic. Stack drilling and thick laminates also need process-specific validation before release.
Best Next Links
Branch to the plastics calculator, drilling calculator, or chip-load calculator when the setup gets specific.
CFRP (Carbon Fiber Reinforced Polymer)
The gold standard of lightweight structural composites. Carbon fibers are extremely abrasive (Mohs 8+), destroying carbide tools in minutes. Diamond-coated or PCD tooling is mandatory for production runs.
| Operation | Tool Type | SFM | Chip Load (1/4" EM) |
|---|---|---|---|
| Edge Trimming | Diamond Coated | 600 - 1200 | 0.003" - 0.006" |
| Edge Trimming | PCD (Brazed) | 800 - 1500 | 0.004" - 0.008" |
| Slotting | Diamond Coated | 400 - 800 | 0.002" - 0.004" |
| Drilling | Diamond / Brad Point | 200 - 500 | 0.002" - 0.005"/rev |
Edge-trimming and slotting rows are the primary workflow here. The drilling row is reference-only on this chart; move to the drilling calculator before you release composite holemaking parameters.
GFRP (Fiberglass / Glass-Reinforced Polymer)
Less abrasive than CFRP but still punishing on tool edges. G10/FR4 (circuit boards) is the most commonly machined GFRP. Coated carbide lasts longer than uncoated but diamond remains the premium choice.
| Material | Operation | SFM (Diamond Coated) | Chip Load (1/4" EM) |
|---|---|---|---|
| G10 / FR4 | Routing | 500 - 1000 | 0.003" - 0.006" |
| G10 / FR4 | Drilling | 200 - 400 | 0.002" - 0.004"/rev |
| SMC / BMC | Trimming | 400 - 800 | 0.003" - 0.005" |
Use the routing and trimming rows as quick reference. Treat FR4 and G10 drilling values as lookup-only until you validate pecking, exit support, and dust control in the drilling workflow.
Kevlar / Aramid Composites
Aramid fibers are tough and flexible — they don't shear cleanly. Standard tools produce fuzzy, delaminated edges. Compression routers or "fishbone" geometry tools are required for clean cuts.
| Operation | Tool Type | SFM | Chip Load (1/4" EM) |
|---|---|---|---|
| Edge Trimming | Compression Router | 400 - 800 | 0.003" - 0.005" |
| Drilling | Brad Point / Dagger | 150 - 300 | 0.002" - 0.004"/rev |
Health & Safety: Composite Dust is Hazardous
Carbon fiber and fiberglass dust is a serious respiratory and skin irritant. OSHA PEL for respirable fibers: 1 fiber/cm³.
- Dust extraction: Dedicated vacuum system at the cutting zone is mandatory. Do not rely on flood coolant alone.
- No compressed air: Never blow composite dust with an air gun — it becomes airborne and inhaled.
- PPE: P100 respirator, safety glasses, long sleeves. Carbon fiber splinters embed in skin.
- Machine protection: Composite dust is conductive — it damages spindle bearings and way covers. Seal and clean frequently.
Frequently Asked Questions
What SFM should I use for carbon fiber (CFRP)?
Edge trimming: 600–1200 SFM with diamond-coated tools, 800–1500 SFM with PCD. Slotting: 400–800 SFM. Higher SFM reduces delamination by producing cleaner fiber fracture.
Why do tools wear so fast on carbon fiber?
Carbon fibers have Mohs hardness of 8+ (harder than carbide at ~9). They mechanically abrade the cutting edge like a grinding wheel. Only diamond-coated, PCD, or CVD diamond tools survive production runs.
How do I prevent delamination when machining composites?
Use compression routers (up-cut + down-cut geometry). Maintain sharp tools — dull edges push fibers instead of cutting. Support both sides of the laminate with sacrificial backing material during drilling.
Should I use coolant when machining carbon fiber?
Default to vacuum extraction at the cut zone rather than assuming coolant fixes the process. Many CFRP laminates do not want flood coolant. If the resin system allows it, light mist can help temperature control, but extraction still does the real safety work.